1、不想每次都除255.0
+ (UIColor *)colorWithR:(CGFloat)red G:(CGFloat)green B:(CGFloat)blue {
return [UIColor colorWithRed:red/255.0 green:green/255.0 blue:blue/255.0 alpha:1];
}
2、随机色
+ (UIColor *)randomColor{
return [UIColor colorWithRed:arc4random()%256/255.0 green:arc4random()%256/255.0 blue:arc4random()%256/255.0 alpha:1];
}
3、以16进制设置色值，如：#FF6752 (以下分是否需要设置alpha)
（1）不需要设置alpha
+ (UIColor*)colorWithHexString:(NSString*)colorStr {
NSString *cString = [[colorStr stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] uppercaseString];
if ([cString hasPrefix:@"#"]) cString = [cString substringFromIndex:1];
if ([cString length] != 6) return [UIColor blackColor];
// Separate into r, g, b substrings
NSRange range;
range.location = 0;
range.length = 2;
NSString *rString = [cString substringWithRange:range];
range.location = 2;
NSString *gString = [cString substringWithRange:range];
range.location = 4;
NSString *bString = [cString substringWithRange:range];
// Scan values
unsigned int r, g, b;
[[NSScanner scannerWithString:rString] scanHexInt:&r];
[[NSScanner scannerWithString:gString] scanHexInt:&g];
[[NSScanner scannerWithString:bString] scanHexInt:&b];
return [UIColor colorWithRed:((float) r / 255.0f)
green:((float) g / 255.0f)
blue:((float) b / 255.0f)
alpha:1.0f];
}
（2）需要设置alpha
+ (UIColor*)colorWithHexString:(NSString*)colorStr alpha:(CGFloat)alpha {
NSString *cString = [[colorStr stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] uppercaseString];
if ([cString hasPrefix:@"#"]) cString = [cString substringFromIndex:1];
if ([cString length] != 6) return [UIColor blackColor];
// Separate into r, g, b substrings
NSRange range;
range.location = 0;
range.length = 2;
NSString *rString = [cString substringWithRange:range];
range.location = 2;
NSString *gString = [cString substringWithRange:range];
range.location = 4;
NSString *bString = [cString substringWithRange:range];
// Scan values
unsigned int r, g, b;
[[NSScanner scannerWithString:rString] scanHexInt:&r];
[[NSScanner scannerWithString:gString] scanHexInt:&g];
[[NSScanner scannerWithString:bString] scanHexInt:&b];
return [UIColor colorWithRed:((float) r / 255.0f)
green:((float) g / 255.0f)
blue:((float) b / 255.0f)
alpha:alpha];
}
